DAX Example tables

Where can I find InternetSales_USD? It's used in the example for this page (https://docs.microsoft.com/en-us/dax/stdevx-p-function-dax).

= STDEVX.P(RELATEDTABLE(InternetSales_USD), InternetSales_USD[UnitPrice_USD] – (InternetSales_USD[DiscountAmount_USD]/InternetSales_USD[OrderQuantity]))